Hammer mill



Aug 19, 1941. I J. VA. F. NEAL HAMMER MILL Filed July 20, 1959 INVENTOR Q.6T7Zea a ma ATTORNEYS 3 73 X6 zfdyw.

Patented Aug. 19, 1941 UNITED STATES PATENT OFFICE HAMMER MILL Joseph A. F. Neal, Buifalo, N. Y.

Application July 20, 1939, Serial No. 285,529

4 Claims.

This invention relates to a hammer mill and more particularly to the type of hammer mill in which a plurality of hammers are swung from a rotating shaft to strike against an adjustable grinding plate installed in the casing of the mill.

One of the principal objects of the present invention is to provide such a hammer mill in which a plurality of fresh jagged cutting edges are presented by the grinding plate to the material being ground, regardless of the degree to which the grinding plate has worn. The maintenance of the grinding plate with a plurality of fresh jagged cutting edges throughout its life insures the rapid reduction of the material by the hammer mill.

Another object of the invention is to provide hammers in such a hammer mill which are similarly formed so as to always present fresh jagged cutting edges to the material to be ground regardless of the degree to which the hammers have worn.

Another object of the invention is to provide a hammer which is held in a fixed axial position on its hammer arm and each of which is at the same time so mounted as to present a new striking side to the grinding plate as the hammer wears, the mounting being also such that the hammers wear uniformly and do not require manual adjustment.

Another object of the inventionis to provide such a hammer mill having the above features in which the hammers and grinding plates having the features embodying the invention can be provided without substantial increase in the cost of the hammer mill.

In the accompanying drawing:

Fig. 1 is an end elevation, partly in section, of the hammer mill embodying my invention.

Fig. 2 is a fragmentary enlarged vertical section of one of the hammers and the grinding plate.

Fig. 3 is a fragmentary horizontal section, taken on line 3-3, Fig. 1.

The invention is applicable to any usual and well known type of hammer mill, that shown including a casing 5 having an inlet 6 for the material to be ground and also having a central horizontal shaft 1 extending through the casing 5 and supported by bearings 8. The shaft I is rotated from any suitable power source (not shown) and within the casing 5 is shown as carrying a plurality of circular plates 9 which in turn carry a plurality of hammer arms I I]. The hammer arms II) are shown as pivotally mounted on pins I I "which extend transversely through the plates 9 parallel with the main drive shaft 1. The arms I0 are thereby free to swing around the pins I I and in operation are thrown radially outward by centrifugal force as the main drive shaft turns.

Each of the hammer arms I0 carries one or more hammers I2 at its outer end, these hammers being of circular form and being mounted for free rotation at the ends of the hammer arms. For this purpose the hammers I2 are shown as mounted on pins I3 carried at the outer ends of the hammer arms II). To insure free rotatability of the hammers I0, the pins I3 can be rotatably mounted in the ends of the hammer arms or the hammers I2 can be rotatably mounted on the pins I3 or both the hammers I2 and the pins I3 can be rotatably mounted. It is important, however, that the hammers I2 snugly fit the pins I3 and that these pins snugly fit the holes in the ends of the hammer arms so that the axes of the various hammers are held at a fixed distance from the I indicated at I4, the perforations I 4 being closely spaced. The purpose of these perforations is to insure the maintenance of jagged cut edges in the hammer throughout its life and regardless of the degree to which the hammer wears.

The hammers I2 coact with a grinding plate indicated generally at I5. This grinding plate is arranged at one side of the casing 5 above the plane of the main drive 1 between horizontal shelveslfi and I! in the casing. A cylindrical perforated plate I8 leads from the shelf IT to a position under and adjacent the material inlet 6, an additional plate I9 being provided to insure the discharge of the materials into the cylindrical perforated plate I3 and against the grinding plate I5. The materials ground by the coaction of the hammers and the grinding plate I5 pass through the perforations of the cylindrical plate I8 to the bottom of the casing 5, the cylindrical perforated plate I8 being arranged concentric with the main drive shaft 1. The ground materials canbe removed from the bottom of the casing in any suitable manner. I

The grinding plate I5 is made up of a plurality of relatively thin metal plates 20 which are arranged face to face and the inner edges of which provide the grinding surface. Each of these plates is of the same size and form, their inner. and outeredges thereof being concentric with the axis of the main drive shaft .1 and each of these plates 20 being made of perforated metal, the perforations being indicated at 2|. As with the hammers I2, the purpose of so perforating the 2 several plates 28 comprising the grinding plate I is to insure the maintenance of jagged cutting edges in the working face of the grinding plate upper and lower ends of the grinding plate sec-- tions 29 as shown in Fig. 1. Each of the bolts 25 extends through slots 26 in the casing 5, these slots being parallel and extending toward the rial to be ground regardless of the degree to which the grinding plate and hammers may be worn.

I claim as my invention:

1. A hammer mill comprising a casing having an inlet for the materials to be ground, a main drive shaft in said casing, a plurality of hammers carried by said drive shaft within said casing and a grinding plateassembly arranged to 00- act with said hammers to reduce said materials, said grinding plate assembly being composed of a plurality of arcuate plates provided with W closely spaced perforations the axes of which are generally parallel with the axis of said main drive shaft, said plates being arranged face to -..-face generally normal to the axis of said main main drive shaft 1'. Upon looseninglthe nutsiz'li of the bolts the grinding plate I5 can be ad justed as a unit toward and from the main driveshaft 1 soas to permit of maintaining the desiredspace between the edges of the hammers and the jagged inner cutting surface of the grinding plate I5. V

5 In operation the materials to be ground are introduced through the inlet 6 and the main drive shaft 1 is rapidly rotated so that the hammerarrns. Ill are swung radially outward. The materials introduced through the inlet 6 are subjected to grinding action between the hammers l2 and the grinding plate I5 and are reduced to a degree which permits their passage through the cylindrical perforated plate it. As wear on any side of the hammers [2 takes place, a con dition of unbalance is created which causes the heavier side ofthe ihammervto swing to the out side and thereby present a fresh side to the grinding plate 25. This action takesplace 'because the hammers l2 are freely rotatable about the axes of the pins 13 and hence as wear takes place on one. side'the opposite side is rendered heavier and hence swings around to coact with the grinding plate IELI AB the same time the hammers I2 areheld in fixed relation, axially, to the hammer arms on which they are mounted and hence act in the same manner as the rigidly mounted hammers heretofore provided.

As weartakes place on the grinding plate IE or the hammers l2, the jagged cutting surfaces of this plate and the jagged edges of these hammers are maintained by the perforations provided. Thus, as the grinding plate I5 wears through one group of perforations 2| it wearsthrough to the next succeeding group of perforations 2l;'the perforations being preferably close- 1y spaced for this purpose. In a similar manner the perforations provided in the hammers l2 in sure the presentation of fresh jagged edges to thematerial regardless of the degree: of weariof the hammers. .Both the grinding plate and the hammers can therefore be worn to a verysub stantial' depth and at no time require sharpening or other treatment to insure their operation at full efficiency From the foregoing it will be seen that the present invention provides ahammer mill which is simple and inexpensive in construction; in

which the hammers are held in fixed relation, axially, on the hammer arms so as to operate at,

full efficiency; in which the hammers wear uniformlyand rotate to present a fresh edge as one side wears so that no'adjustrnent of the hammersion the ends of the hammer arms need be provided and in which boththe grinding plate and theuhammers are so constructed as to al-.

wayspresen't jagged cutting edges to the matedriveshaft and with their edges facing said main drive shaft and means for holding said arcuate plates in assembled relation comprising upper and lower bolts extending through the upper and lower-"ends of said plates parallel with saidfma'in drive shaft, the ends of said bolts being received and secured in slots in said'casing extending'toward said main drive shaft whereby said bolts and the assembled plates carried thereby can be adjustably'positioned along said slots concentrically toward and from said main drive shaft, the perforations of said plates providing a plurality of internal. holes in said grinding plate assembly whereby the wearing of said grinding plate serves to continuously expose fresh jagged'edges to said materials.

2. A hammer mill comprising a casing having an inlet for the materials to'be' ground, amain. drive shaft in said casing, a plurality of hammer arms carried by said drive shaft within said casing, a hammer mounted on each of said hammer arms and a grindingplate arranged to coact with said hammers to reduce said materials, each of, said hammers being composed of metal disks rotatably'mounted on the end of the corresponding hammer arm and having a plurality of per-' forations extending therethrough parallel with said main drive shaft whereby the wearing of said hammers serves to continuously expose fresh jagged edges to said materials and said grinding plate being composed of a plurality of arcuate plates provided with closely spaced perforations the axesof which are generally parallel with the axis of said main drive shaft, said plates being arranged face to face generally normal to the axis of said main drive shaft andjwith their edges facing said main drive; shaft and means for holding said arcuate plates in assembled relation comprising upper and lower bolts extending through the upper and lower ends of said plates parallel with said main drive shaft, the ends of said bolts being received and secured in slots in said casing extending toward said main'drive shaft whereby said bolts and theas sembl-ed plates carried thereby can'be adjustably positioned along said slots, the perforations of said plates providing a plurality of internal voids in the assembly of grinding plates whereby the wearing of said assembly serves to continuously expose fresh jagged edges to; said materials. t a i l i 3. A hammer mill comprising a casing having an inlet for the materials to be gtOund,-amain drive shaft in said casing, a plurality of hammer arms carriedbytsaid drive shaft within said casing,a substantially circular disk forming a hammer and rotatably mounted at its center of gravity on the end of each of said hammerarmsto rotate around a fixed axis arranged parallel with the axis of said main drive shaft and a grinding plate arranged beyond said hammers to coact with said hammers to reduce said materials, said hammers being freely rotatable during the grinding operation whereby the wearing of one side of any hammer causes the hammer to rotate under centrifugal forces imposed thereon to present a fresh edge to said grinding plate and each of said hammer disks having a plurality of closely spaced perforations extending therethrough parallel with said main drive shaft whereby the wearing of said hammers serves to continuously expose fresh jagged edges to said materials.

4. A hammer mill comprising a casing having an inlet for the materials to be ground, a main drive shaft in said casing, a plurality of hammer arms carried by said drive shaft within said casing, a substantially circular disk forming a hammer and rotatably mounted at its center on the end of each of said hammer arms to rotate around a fixed axis arranged parallel with the axis of said main drive shaft and a grinding plate arranged beyond and in opposing relation to said hammers to coact with said hammers to reduce said materials, said hammers being freely rotatable during the grinding operation whereby the wearing of one side of any hammer causes the hammer to rotate under the centrifugal forces imposed thereon to present a fresh edge to said grinding plate and said grinding plate being composed of a plurality of arcuate plates provided with closely spaced perforations the axes of which are generally parallel with the axis of said main drive shaft, said perforated plates being arranged face to face generally normal to the axis of said main drive shaft and with their edges facing said main drive shaft and means for holding said perforated plates in assembled relation, the assembled grinding plates being thereby provided with a plurality of internal:

holes whereby the wearing of the assembled grinding plates serves to continuously expose fresh jagged edges to said materials.

JOSEPH A. F. NEAL. 

